Lower leg walkers are a class of off-the-shelf ankle foot orthosis developed in the USA early in the nineteen-eighties. An ankle foot orthosis is a device fitted to the ankle and foot to provide at least a partial substitute for some of the functions of the ankle joint. In the case of lower leg walkers, the main application is in assisting the ligamentous structures of the joint to resist inversion and eversion and in some cases to immobilize the joint.
Lower leg walkers have a foot platform and extend proximally about the ankle and lower leg, normally ending a short distance below the knee. Their structural antecedents are below knee plaster casts and traditional orthoses, such as those used for the victims of poliomyelitis and cerebral palsy. The main aim of those orthoses is to help patients with walking difficulties to walk more easily. It remains common practice to build orthoses which combine a double acting or other ankle hinge with a foot platform, often one having a rocker sole, in order to limit ankle travel and facilitate ambulation.
Indications for lower leg walkers have been extended by orthopaedic surgeons and orthotists. In the U.S.A. most seem to agree that they are indicated in non-displaced ankle fractures, march fractures, severe sprains and post-operative use following certain ankle ligament reconstructive procedures.
Polakoff et al, Orthopedics November 1984 Vol 7/No 11: 1712-1715, trialling an early lower leg walker, stated that " . . . the treatment of stable ankle fractures with an ankle foot orthosis (of the lower leg walker type) can significantly decrease the time until clinical union, and the complication of "fracture disease" associated with plaster immobilisation. Specifically, posttreatment tenderness, edema, and atrophy were diminished, while range of motion was maintained." They go on to say future investigations should explore other types of ankle injuries and surgically stabilized conditions using orthoses of this type.
Only a small number of workers has actually published in this field. In 1989, Neumann et al reported significantly less muscle wastage and joint stiffness in healthy volunteers wearing lower leg walkers than in a comparable group in short leg casts. They also refer to 48 cases of injured lower limbs treated in lower leg walkers including foot, lower tibia and fibula injuries as well as ankles. A somewhat different orthosis was investigated earlier by Stover and York whose 164 cases included numerous fractures of tibia and fibula including 9 cases of compound fractures of tibia and fibula.
There is a dearth of good comparative studies on the efficacy of lower leg walkers versus standard treatments in any condition other than ankle fractures. However, in 1993, Klenerman's group in Liverpool, U.K. completed a study of early mobilization versus plaster immobilization following operative repair of ruptured Achilles tendon. They used hinged lower leg walkers designed by the present authors. Scanning techniques were used to assess rates of healing of the tendon with each method and objective assessment of rehabilitation was also employed. The results were favorable to the lower leg walker regime.
Nowadays, it is generally accepted that mobilization soon after injury produces benefits. Treatment is generally directed to shortened rehabilitation periods and benefits include a quicker return to function and better ultimate outcome. There is less loss of muscle bulk, oedema subsides more rapidly and diminution in proprioception is minimized. In stable ankle fractures, severe sprains and certain foot fractures, most of the benefits may be realized within a regime utilising a lower leg walker, without hinges, in which the patient walks according to a protocol laid down by the carer. On the other hand, more demanding protocols may be employed when a hinged walker is used. As an ever widening group of patients is being treated with this type of orthosis, it is clear that the greatest benefit from any invention relating to lower leg walkers will be gained if it can be applied to both hinged and non-hinged types.
So far as we have been able to ascertain, there is little objective evidence to demonstrate either the efficacy or safety of `conventional` lower leg walkers in treating any fracture of the tibia or fibula. Only the recent Klenerman study applying to walkers designed by the present authors suggests that they have a definite, safe place in the post-operative treatment of surgical repairs to ruptures of the Achilles tendon. Nevertheless, it is known that large numbers of these devices are used in the treatment of both these categories of injury.
Only a small number of lower leg walkers is used outside the USA and Canada. However, the concept has now been established long enough to overcome the conservatism of surgeons and orthotists in Europe. Even so, it seems unlikely that the acceptance in Europe will reach the levels seen in North America before the end of the century.